In video system applications, random noise present in analog video signals, such as NTSC or PAL signals, for example, may result in images that are less than visually pleasing to the viewer. To address this problem, noise reduction (NR) operations may be utilized to remove, at least partially, the analog noise present. Traditional NR operations use either the infinite impulse response (IIR) filtering based method or the finite impulse response (FIR) filtering based method. IIR filtering can significantly attenuate high frequency noise. However, some NR operations may result in visual artifacts such as motion trails, jittering, and/or wobbling at places where there is object motion if the amount of filtering is not conservative enough. Setting the IIR filtering conservatively will mitigate the noise removing capability, even for places where is no or little motion, such as a static area in the video, resulting in many instances where objectionable noise artifacts remain in the video signal. [Note: this invention is about noise reduction.
Other traditional NR operations may be FIR filtering based. FIR-based filtering is not subject to the artifacts of motion trail, motion blurry, jittering and/or wobbling as much as IIR-based filtering is. It may provide acceptable perceptual quality for moving areas. But in practical NR system, which cannot employ a large number of video images to perform FIR filtering (due to cost considerations), its noise reducing power is very limited for areas of no or little motion.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.